The Tories have been in charge for 2/3 of the time over the last 70 years or whatever, the charts for each are roughly the same, no one is better than the other for the economy, but there are external things which can absolutely batter it. The big problem for the Tories this time around is Brexit, which is largely their own doing (and a lot of traditional labour voters doing to).
You're looking at it far too simplistically, there are about 200 years of GDP data which shows times after recessions are crap, and the depth of the recession is largely proportional to the time it takes to recover. Look at the great depression for example, which took nearly 20 years to recover from, same with any of the wars etc. Shorter ones are easier to handle.
Also, it's hard to grow after you've grown, this is why we will never keep up with the likes of India, China or whoever else in the future, we've had our time, the more recent and future growth is there's. Even more so since the population stopped rapidly increasing in the UK after the baby boom etc.
Also your very first graph was for production, not the economy. We've scaled back on production as we were getting battered by the EU and Asia, and shifted over to services. Brexit will kill off any growth in production for the foreseeable.
Look at the long-term GDP below, pretty consistent curve, but every time we got ahead of the curve there was a recession to bring it back on track, the same applies to anyone, like USA, France, Germany etc, and it doesn't care who they have in power either.
Comparing different times is ludicrous if you're not going to consider the effects of Wars, Recession, major disasters etc, and also compare that to how the other nations got on during these times. IF you're doing **** relative to the others then you're doing ****. If everyone is doing ****, then it's largely not your fault. If you shoot yourself in the foot (Brexit) compared to the others, then this is worse than all.
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