It also started not long after man first stepped on the moon but before Channel 4 launched. There have been quite a few things that have happened in the period of time we have been part of the Common Market and its successors so if your only argument is "time frame" it doesn't have much substance to it.
National debt - mostly due to government policy and international events...which are linked. The UK/US decision to deregulate anything that moved in the 80s, including financial services, has been the single biggest contributor to our national debt since the second world war. It would have happened whether we were in the EU or not.
As for poverty wages - this has been looked at time and time again. Other than a minimal impact at the lower end of the wage scale caused by immigration - how else has being in the EU caused that problem?