1994 changed professional football forever: it was the year the NFL introduced the salary cap in order to increase parity and competitiveness within the league. The plan worked as there have been 13 different Super Bowl winning teams since the cap was put in effect 23 seasons ago. There have been only 12 different champions in the 27 seasons of the pre-cap era.
The first salary cap was set at $34.6 million (which would be worth about $55.3 million in 2016). Ever since that first season, the cap space has consistently grown. It has reached a new height in 2016: according to multiple media reports, the NFL and the NFL Player Association have agreed to set the 2016 salary cap at $155.27 million. Compared to 2015, the cap, which is calculated based on the league's yearly revenues, has increased $11.99 million.
Due to the increase, the New England Patriots' inofficial cap space is now currently $13.56 million, as the team has an adjusted cap number of $159.86 million due to a 2015 cap carryover of $1.35 million and predicted bonus adjustments of $3.19 million (all numbers via patscap.com).
While New England is in the bottom third when it comes to cap space, the team is actually not in bad financial shape. The Patriots have no major players hitting free agency and could create additional cap space either via extensions or contract restructures.