I could find easily sorted statistics in only one place, (
www.footballdb.com) and they only went back to the 2012 season, but those statistics tell a tale of more than just defense.
2016 Rushing Defense YPG: Iowa 149.7, Wisconsin 98.8
2016 Passing Defense YPG: Iowa 187.2, Wisconsin 187.0
2016 Total Defense YPG: Iowa 336.8, Wisconsin 285.8
2016 Total Defense PPG: Iowa 18.8, Wisconsin 15.6
2016 Rushing YPG: Iowa 171.8, Wisconsin 203.1
2016 Passing YPG: Iowa 136.5, Wisconsin 168.4
2016 PPG: Iowa 24.9, Wisconsin 28.4
2015 Rushing Defense YPG: Iowa 121.4, Wisconsin 95.6
2015 Passing Defense YPG: Iowa 204.1, Wisconsin 155.9
2015 Total Defense YPG: Iowa 325.5, Wisconsin 251.5
2015 Total Defense PPG: Iowa 20.4, Wisconsin 13.7
2015 Rushing YPG: Iowa 181.7, Wisconsin 150.3
2015 Passing YPG: Iowa 188.6, Wisconsin 215.8
2015 PPG: Iowa 30.9, Wisconsin 26.8
2014 Rushing Defense YPG: Iowa 168.3, Wisconsin 126.1
2014 Passing Defense YPG: Iowa 163.4, Wisconsin 150.0
2014 Total Defense YPG: Iowa 331.7, Wisconsin 276.1
2014 Total Defense PPG: Iowa 25.6, Wisconsin 20.8
2014 Rushing YPG: Iowa 163.1, Wisconsin 320.1
2014 Passing YPG: Iowa 225.7, Wisconsin 141.6
2014 PPG: Iowa 28.2, Wisconsin 34.6
2013 Rushing Defense YPG: Iowa 128.4, Wisconsin 102.9
2013 Passing Defense YPG: Iowa 164.8, Wisconsin 191.4
2013 Total Defense YPG: Iowa 293.2, Wisconsin 294.3
2013 Total Defense PPG: Iowa 18.9, Wisconsin 16.3
2013 Rushing YPG: Iowa 180.2, Wisconsin 283.8
2013 Passing YPG: Iowa 192.4, Wisconsin 189.8
2013 PPG: Iowa 26.3, Wisconsin 34.8
2012 Rushing Defense YPG: Iowa 162.1, Wisconsin 128.9
2012 Passing Defense YPG: Iowa 213.7, Wisconsin 179.1
2012 Total Defense YPG: Iowa 375.8, Wisconsin 308.1
2012 Total Defense PPG: Iowa 22.9, Wisconsin 19.1
2012 Rushing YPG: Iowa 123.0, Wisconsin 236.4
2012 Passing YPG: Iowa 174.4, Wisconsin 139.9
2012 PPG: Iowa 19.3, Wisconsin 29.6