To wrap up the year, I’m looking back at some of the most significant political events of the past 12 months and picking 14 charts that sum up what I think were the most memorable trends, winners and losers.

The first seven charts appeared yesterday; here are the remaining seven.

8. The Lib Dems’ brush with 0%

In the Rochester & Strood by-election in November, the Lib Dems won 0.87% of the vote. It was enough to get them rounded up to 1% rather than down to zero. But this was still the worst share of the vote the party has ever achieved, lower than the previous record of 1.2% set by the Liberal party in the 1948 by-election in Glasgow Camlachie. I doubt the party cares much about these lamentable performances anymore. But it’s worth reminding ourselves of how the Lib Dems – a party of government, lest we forget – has fared in the 19 by-elections it has contested during this parliament:

9. History is not on the Tories’ side

Here’s the Conservative share of the vote in every election since the war in which it has won power:

It’s a not uncommon observation that the Tories’ share of the vote has declined sequentially in every election since 1955 in which it has ended up in government. And it is a persuasive trend. Even during the Thatcher years, the share of the vote continued to fall, albeit not as as rapidly as during other decades.

If this trend continues, it will be incredibly tricky for the Tories to even end up the largest party at the election. A “35% strategy”, once allegedly favoured by Ed Miliband, just won’t do for the David Cameron. Unlike Labour, the Tories need to be on 36% to at least be in with a chance of dictating the terms of a new coalition.

10. Labour is down but not out

Labour’s monthly poll average ended 2014 almost five points below where it began. Yes, it’s not been a consistent decline. From May to August the average went up in the polls, before resuming a descent. Nonetheless the overall trend has been downwards and it is one that has changed profoundly many people’s expectations for the election result. At the start of the year it would have been fair to assume Labour was heading for a majority in parliament. At the end of the year it would be wise to assume anything but. The party’s average for December (33.4%) is its second lowest monthly score since 2010:

11. Northern Ireland: potential kingmaker

The 18 parliamentary seats in Northern Ireland are normally treated as a bit of an afterthought at a general election. They are not contested by any of the main British political parties, and are always the last to declare, their results tending to trickle in long after the polls are closed and when the identity of the new government is already known.

But those 18 seats may become a whole lot more consequential in 2015 if there is a hung parliament (which is very likely) where no two parties are able to agree on forming a coalition (which seems increasingly likely).

It could then be the case that Northern Ireland’s MPs turn from courtiers to kingmakers, and a tiny number of seats take on a huge significance.

12. Heywood & Middleton was not a Labour stronghold

The media made much reference to this seat being “rock solid” or “very safe” for Labour. It wasn’t. Jim Dobbin’s majority in 2010 was only 5,791: very close to what would technically be called a marginal. Up to the 2010 general election Heywood was indeed a stronghold: in 2005 Dobbin’s majority was 11,083. But since 2010 the seat has been what could be classed “provisionally safe”: the kind Labour could and should be able to defend fairly comfortably, so long as nothing is taken for granted:

There are dozens of seats like this across the country. The incredibly close result of October’s by-election ought to encourage the party to pay those seats rather more attention.

13. There is such a thing as anti-Ukip tactical voting

In the Newark by-election in June, some Labour and Liberal Democrat supporters indulged in a spot of tactical voting. Anecdotal evidence from the three main parties suggested that voters sought to minimise Ukip’s likelihood of success. People who would ordinarily have backed Labour or the Lib Dems appeared to have voted Conservative, whose candidate was perceived as being the most likely to ensure Nigel Farage’s party missed out on first place.

As it turned out, the Tories held the seat quite comfortably:

The circumstances in which the by-election was called had no significant impact upon the Tory vote. Former MP Patrick Mercer resigned after he was suspended from the Commons for six months for allegedly asking questions in parliament in return for money. But this did not seem to prompt a backlash among constituents towards Mercer’s party. Something similar took place at the Eastleigh by-election in 2013. The Liberal Democrats held on to the seat, despite the contest being triggered by the party’s former MP Chris Huhne resigning after admitting lying to police over a speeding offence.

14. The SNP will struggle to win more than 20 seats from Labour

Ignore the polls and the hysterical headlines. There are no easy seats for the SNP to win from Labour. This is not a new observation, but it’s one that often gets overlooked in some of the breathless reporting of the latest Scottish polls or political in-fighting.

The truth is no Labour constituencies would fall to the SNP on a swing of 5%. For one seat to change hands, the party needs a swing of 5.2%, which would deliver them Ochil & South Perthshire.

And it doesn’t get any easier. Just three of Labour’s 2010 haul of 41 seats would fall to the SNP on a swing of 10%. As the following chart shows, only when the SNP’s swing gets above 10% are the greatest number of Labour seats at risk:

I remain utterly unpersuaded that the SNP is going to carry out a “bloodbath” of Labour seats in May. If there’s one thing above all that 2014 has revealed, it’s that the general election is not going to be a story of uniform swings across the country or even across separate parts of the country. It will be 650 individual contests whose outcome cannot be anticipated by or extrapolated from opinion polls. And this is why it will be the most unpredictable and exciting election for a generation.