Mathematics · Data Interpretation

Four institutes (A, B, C, D) had contracts with four vendors (W, X, Y, Z) from 2010 to 2019. Each institute and vendor had exactly two contracts. Z had at least one contract every year. X had contracts up to 2015, but none after. Y had contracts in 2010 and 2019. W had contracts only in 2012. There were five contracts in 2012. There were exactly four multi-year contracts: B had a 7-year contract, D had a 4-year contract, and A and C had one 3-year contract each. The other four were single-year contracts. C had contracts in 2012 but none in 2011. B and D each had exactly one contract in 2012. D had no contract in 2010. In which of the following years were there two or more contracts?