Widest Path For Waltheri

Moves 1 - 3  

(41,192 games - 56.9%): The hoshi. Popular alternative at a, the komoku (29,252 games - 40.4%).
(20,883 games - 50.7%): The adjacent hoshi. Popular alternative at b, the opposite hoshi (12,083 games - 29.3%).
(8,835 games - 42.3%): Black plays a parallel opening with this komoku. Very close alternative at the other komoku c (8,584 games - 41.4%), which leads into the high Chinese and low Chinese fuseki.

Moves 4 - 6  

(5,277 games - 56.2%): White takes the empty corner with this komoku. Popular alternative at a (3,393 games - 36.1%), the hoshi.
(2,200 games - 29.2%): Black makes a small low shimari, playing the orthodox fuseki. Popular alternative at b (1,662 games - 22.1%), which makes a high approach to the komoku. Another often-played alternative is at c (1,420 games - 18.9%), making a low approach.
(798 games - 36.2%): The wedge. Popular alternative at d (645 games - 29.2%), the low approach to the hoshi.

Moves 7 - 8  

(277 games - 37.5%): The low approach. Popular alternative at a (168 games - 21.1%), the high approach.
(130 games - 43.5%): White plays a three-space low pincer. As far as I can tell, White hasn't played this pincer since 2013. Most of the professional interest in the rest of the path seems to centre around 2006 - 2011. Popular alternative at b (86 games - 28.8%), the two-space high pincer.

Moves 9 - 14  

(66 games - 50%): A press.
(65 games - 98.5%): Only Hong Kipyo deviated here, playing the thrust up.
(65 games - 100%): The first 100% consensus on a move of the path.
(35 games - 53.6%): Popular alternative at a (28 games - 43.1%), the keima. (35 games - 100%)
(35 games - 100%)

Moves 15 - 20  

(28 games - 80%): Attacks the white stone.
(16 games - 57.1%): Jumps out. Popular alternative at a (10 games - 35.7%), the counter-pincer.
(16 games - 100%): Makes a two-space base.
(10 games - 62.5%)
(6 games - 60%)
(4 games - 66.7%)

Moves 21 - 22  

(2 games - 50%). The alternative moves played here are a and b, with one game each.
(2 games - 100%)

Moves 21 - 22  

(2 games - 100%)

This is the end of the path. At this point, Zhou Junxun hane'd at a in 2008; whereas Kobayashi Koichi hane'd at b in 2009. From the data, it seems to me that the three-space pincer at was a fad for some time around 2006 - 2007, before being exhausted or refuted, causing the pros to eventually move on by around 2011.

- bugcat, 8-9k at time of writing