An addition to this post on 5 year averages using NOAA data. This time I am using UK Met Bright Sunshine data.
1) The current 5 year period has less bright sunshine than the previous 5 year period.
2) The previous 5 year period had no large negative anomalies, and no unusual positive anomalies, yet it was the most sunshine since 1929.
3) The period from 1988 to 2008 was the longest without a -50 hour anomaly.
4) The large negative anomalies are returning to normal.
sunshine hours 
Check my report on Max Daily Temps vs Bright Sunshine Hrs Central UK 1930 – 2010, Tallblokes Talkshop.
I’m looking for same data for contiguous US, but says not done now, but I’d do historical without conversion.