You might want to check FTDNA's
Scotland Y-DNA Project. It is so far the largest and most detailed database for Scottish Y-DNA.
There are about 9% of Germanic haplogroup I1. The rest is less clear. Most of the R1a (8.5%) and I2b (4%) is probably Germanic too, although some of it might be Celtic. Haplogroup Q (0.5%) is surely of Scandinavian origin.
R1b is mixed Celtic and Germanic. Here is a small analysis.
Not all R1b members tested for subclades, but among those who did I counted 66 Germanic R1b1a2a1a1
a, aka R1b-U106 (12.5%) and 470 predominantly Celtic R1b1a2a1a1
b (87.5%). The latter includes :
- 60 Irish-Scottish R1b-M222 (12%)
- 31 purely Scottish R1b-S68 (6%)
- 31 Italo-Gaulish R1b-U152 (6%)
- 11 mostly Franco-Iberian R1b-SRY2627 (2%)
The others are undefined. There are 205 R1b-L21 (38%), which is the most common kind of R1b in Britain. It is found all along the Atlantic coast from Iberia to Norway, as well as in Germany. It could be just as well Celtic or Germanic. In the Netherlands and Scandinavia, L21 is found is approximately the same proportions as U106. So it is fair to assess that 12.5% of Scottish L21 is Germanic and 25.5% is Celtic.
Within R1b, 12.5% is Germanic R1b-U106 and 12.5% is Germanic R1b-L21. One fourth of R1b is Germanic, and three fourth Celtic. As 72.5% of Scots are R1b, it means that about 18% of all Scottish haplogroups are Germanic R1b.
The total for Germanic lineages (I1, I2b, Q, R1a and Germanic R1b) is therefore about 40%.
Middle Eastern haplogroups (G2a, J2, E1b1b, T), which account for 4.5% of Scottish lineages, might have come to Britain during the Neolithic, or through continental Celts, Romans and Germanic tribes. It's probably a bit of everything, though nobody knows in which proportion. Let's say that 2.5% is of Germanic origin to keep the proportions with average haplogroup frequencies in the Netherlands and Norway, the source countries of the Anglo-Saxons and Vikings in Scotland.
This gives us 42.5% of lineages of Germanic origin. The rest (57.5%) can be considered Celtic.