BERLIN, April 15 (Reuters) - Germany’s COVID-19 restrictions have led households to put aside some 200 billion euros ($239.54 billion) and this money is likely to boost overall economic growth once curbs are lifted and consumers can splash out during summer, leading think tanks said on Thursday. ($1 = 0.8349 euros) (Reporting by Michael Nienaber, editing by Kirsti Knolle)