They prove Federer had prime ATG competition on at least 1 surface. Djokovic had 0.
Therefore 2005-2007>>>>>>>>>> 2014-2016.
They can be listed by surface too.
Hardcourt
2004: no.4 Federer, no.78 Roddick, no.83 Hewitt, no.106 Safin, no.145 Agassi
2005: no.11 Federer, no.122 Hewitt, no.124 Nadal, no.139 Agassi
2006: no.2 Federer, no.114 Blake
2007: no.6 Federer, no.55 Djokovic, no.145 Nadal
2014: no.16 Djokovic, no.18 Federer, no.95 Cilic, no.96 Wawrinka, no.99 Nishikori, no.131 Berdych
2015: no.1 Djokovic, no.32 Federer, no.62 Murray, no.101 Wawrinka
2016: no.9 Djokovic, no.13 Murray, no.85 Wawrinka, no.132 Nishikori
Clay
2004: no.56 Coria, no.70 Gaudio, no.113 Moya
2005: no.5 Nadal, no.141 Gaudio, no.144 Coria
2006: no.9 Nadal, no.86 Federer
2007: no.6 Nadal, no.63 Federer
2014: no.17 Nadal, no.71 Djokovic
2015: no.39 Djokovic, no.77 Wawrinka, no.113 Murray, no.121 Nadal
2016: no.22 Djokovic, no.57 Murray, no.134 Nadal
Grass
2004: no.21 Federer, no.89 Roddick
2005: no.12 Federer, no.89 Roddick
2006: no.12 Federer
2007: no.26 Federer
2014: no.34 Djokovic, no.89 Federer
2015: no.26 Djokovic, no.85 Federer
2016: no.12 Murray, no.104 Raonic