For the sake of simplicity, I've made the following easy formula to hypothetically measure impact out of curiosity...
0.5* Spotify #s + 0.5 * approx. YT #s = #/1000000 = impact count.
YT count includes the music video, lyric video, and/or official audio uploaded directly to the official channel of the artist. BTS videos, previews, performances, and parodies were not included.
I advise not comparing 2013 #s to 2014 #s, only compare them within the same year for accuracy! Streaming is relative and the power has increased significantly industry-wide since 2013.
*Taylor has been left out because Spotify.
2014
Katy Perry - Dark Horse (feat. Juicy J) 0.5 (300.19M) + 0.5 (83.30M + 1.05780B) =
720.65
Pharrell Williams - Happy 0.5 (355.35M) + 0.5 (24H thing: 181.15M + 706.42M + 20.03M + 5.10M + 114.97M) =
691.52
Meghan Trainor - All About That Bass 0.5 (280.88M) + 0.5 (3.96M + 968.25M) =
626.55
Pitbull - Timber (feat. Ke$ha) 0.5 (308.22M) + 0.5 (39.91M + 11.56M + 647.98M) =
503.84
MAGIC! - Rude - 0.5 (299.27M) + 0.5 (32.66 M + 614.83M) =
473.39
John Legend - All of Me 0.5 (343.53M) + 0.5 (0.66M + 576.31M + 2.77M) =
461.64
Iggy Azalea - Fancy (feat. Charli XCX) 0.5 (230.65M) + 0.5 (598.92M) =
414.79
*my guess is SIO would be around where AATB is.
*Blank Space would probably be inbetween AATB & Timber as well, around SIO.
2013
Katy Perry - Roar 0.5 (213.09M) + 0.5 (81.98M + 1.01996B) =
657.52
Miley Cyrus - Wrecking Ball 0.5 (184.81M) + 0.5 (25.66M + 788.79M + 52.38M) =
525.82
Macklemore & Ryan Lewis - Thrift Shop (feat. Wanz) 0.5 (253.10M) + 0.5 (746.49M) =
499.80
Lorde - Royals 0.5 (269.97M) + 0.5 (499.54M + 61.72M) =
415.62
Robin Thicke - Blurred Lines (feat. T.I. & Pharrell) 0.5 (245.96M) + 0.5 (405.03M + 40.34M) =
345.67
Macklemore & Ryan Lewis - Can't Hold Us (feat. Ray Dalton) 0.5 (328.44M) + 0.5 (330.88M) =
329.66
P!nk - Just Give Me a Reason (feat. Nate Reuss) 0.5 (178.52M) + 0.5 (52.90M + 421.39M) =
326.41
Bruno Mars - Locked Out of Heaven 0.5 (206.40M) + 0.5 (361.55M) =
283.98
Eminem - The Monster (feat. Rihanna) 0.5 (230.49M) + 0.5 (316.03M) =
273.26
Bruno Mars - When I Was Your Man 0.5 (172.14M) + 0.5 (326.89M) =
249.52
*let's not even bother w/ Harlem Shake*