I did the sampling thus:
I brought up a 5 generation pedigree at Ben Laible's mspedigree.com on each bitch. In the 5th generation are 32 ancestors, of which 16 are female. I traced each tail female line back, on the bottom tail female line, to the first apparent import.
These are the sum total of the bitches I found at the bottoms of these female lines. There were no others, save for a single occurance of a German bitch who came in through import of a son.
Ch.Amsel VD Cyriaksburg is far and away the most represented, which was my expectation. She was the foundation of Marienhof, along with the two daughters she whelped upon arrival from Germany. Amsel left lines through 6 daughters, 2 sons.
Can.Ch.Nette V Mumingtal is still represented in some lines. The first Canadian Champion, she was owned by Anne Eskrigge. She left two producing daughters.
Christel VD Fallerburg shows up sporadically as well, through two daughters. She also had a son.
Alma VD Zunkunft also leaves modern lines of descendants, all those coming down through a great grandaughter of mostly Marienhof breeding, Amarantha of Ravenroyd. She appears to have been acquired by Marienhof, and so is represented in a few tail-female bitch lines.
Galeria V Abbagamba. Any pedigree rich in Glen-Sed (Sky Rocket) will have lots of Galeria behind it. She was a black. She left three daughters.
Showing up twice only, through different daughters, is Elfe V Bretanopark, though she is shown leaving 4 daughters and a son.
Adford's Tam Terrific Amsel 16 Penlan Cadet Too Penlan Amsel 16 Suelen Upsee Daisy Suelen Amsel Christel 13 3 Felds Segelschlitten Feldmar Amsel Nette Galeria* Alma 6 2 7 1 *lots of Glen Sed linebreeding Minquas Blythe Spirit Blythewood Amsel Christel Alma Carmen Heinzelmannchen [germany] 13 1 1 1 Orbits Lift Off Skyline Amsel Nette Alma* 7 2 7 *6 lines due to being linebred on Melmar's Jack Frost Peni Pride of Ramel Platz Rampage Amsel Christel Alma 13 1 2 Jana PD Regency Amsel Nette Alma Elfe 10 3 2 1 Jobie Repitition Amsel Nette Galeria Christel Alma 10 1 3 1 1 Hilda V Sole Baye Amsel Nette Galeria Alma Elfe 10 2 2 1 1 La May's LIttle Goldilocks Fancway Amsel Alma 10 6 Fancway's Vampira Valharra Amsel Alma Christel 14 1 1
12 bitches, with a total of 7 tail female ancestors in 192 bitch lines. 138 end in Ch.Amsel VD Cyriaksburg. And wait till you look at Display's background ... 14 of his 5th generation female tail lines trace to Amsel. One line traces to Frefrau Heinzelmannchen (Germany) and the last to Ch.Halowel Vega. (in fact he traces to Amsel a total 68 times!)
For all intents and purposes, this suggests that our breed is currently comprised of the genetic contribution of Amsel, Display and about 3 other bitches. While there were other imports, especially among blacks, they take up very small percentages of the overall picture. All totalled, I doubt they'd take up more than 1% of the gene pool, though it may be slightly higher in color bred families.