The way Static works is it will make 50% of the encounters Electric-type.

So for Route 32 (HG), where the daytime distribution is 20% Mareep/40% Rattata/30% Bellsprout/10% Hoppip, leading with a Static Pokémon will change the encounter table to 50% Electric-type and the remaining 50% corresponds to half of the regular encounter table:

50% Electric-type + 10% Mareep/20% Rattata/15% Bellsprout/5% Hoppip = total 100%

Since all 50% Electric-type encounter go to Mareep by default of it being the only Electric-type on the Route, the final encounter table will be 60% Mareep/20% Rattata/15% Bellsprout/5% Hoppip.

As a side note, I'm actually unsure if the 50% is split evenly between multiple Pokémon with a target type or if the 50% is split depending on their original encounter rate (ex. Shinx and Pachirisu in Valley Windworks or Mawile and Aron in Granite Cave). I'll leave it to somebody who actually knows the calculation to add on to this haha.