Even in the face of declining TV ratings, lower attendance and other issues, the National Football League was able to leverage some positive developments into strong sponsorship growth this past year.Sponsorship spending on the professional football league and its 32 teams rose 5.9 percent to $1.32 billion in the 2017-2018 season, according to ESP research. Spending rose 4.3 percent in the previous season.The increase exceeds the year-over-year increase in 2017 sports spending and overall North ...