Mosquito IV finished production in June 1943, with 273 built as bombers, there were 54 mark IX bomber April to November 1943, mark XVI bomber production began in November 1943, with 109 built to end June 1944.
To start with Mosquito HE loads only, Bomber Command Mosquitoes dropped 758x250 pound HE bombs for the war and after dropping 10 of them on the night of 3/4 November 1943 only dropped another 21, the last on 11 March 1944. Mosquitoes first dropped Target Indicators on 27 January 1943.
1942 raids, ratio of 500 pound to 250 pound HE
May 1 to 1
June 1.1 to 1
July 1.7 to 1
August 2.3 to 1
September 20.6 to 1
October 31.9 to 1
November, December 341x500 pound and no 250 pound bombs dropped. January to May 1943 1,706x500 and 66x250 pound HE, 307x250 pound incendiary, 208 of the TI where no HE bombs were dropped. Also mostly in February 1943 loads of 3x500 pound were being carried.
The period June to October 1943 saw 2,050x500 and 535x250 pound HE bombs dropped or around 3.8 to 1, nightly figures routinely report a 3x500 and 1x250 pound load. Add the 681x250 pound target indicators and the ratio is 1.7 to 1. To type slowly, removing the 361 TI dropped on targets when there were no HE bombs dropped leaves a ratio of 2.4x500 pound to 1x250 pound. Given the number of nights when the Mosquito force was a mixture of bombers and pathfinders it seems clear enough most sorties with 500 pound bombs on board the ratio was 3 to 1 with exceptions, in November 1943 it was 1,263x500 to 15x250 pound and from then on HE loads were usually 4x500 pound unless a 4,000 pound bomb could be carried.
All this when from 1942 into early 1944 the majority of Mosquitoes with Bomber Command were mark IV and the arrival of the Canadian built types which were roughly mark IV equivalents.
As examples,
30 August 1943
11 Mosquito attacked Munchen-Gladbach,3x500, 1x250 pound HE, 32x250 pound TI (Main force target)
10 Mosquito attacked Duisberg 30x500, 1x250 pound HE, 2x250 pound TI
3 Mosquito attacked Foret D'Eperleques, 12x250 pound TI
For the night 33x500, 2x250 pound HE, 46x250 pound TI.
23 September 1943
6 Mosquito attacked Mannheim 24x250 pound TI (Main force target)
8 Mosquito attacked Darmstadt 24x500 pound HE, 8x250 pound TI (Diversion)
6 Mosquito attacked Aachen 18x500 and 6x250 pound HE
HE only raids 24, 25 and 26 September 1943
23 Mosquito attacked various targets 69x500 and 23x250 pound HE
From May 1944 onwards the reporting splits Mosquito sorties into Oboe and non Oboe.
Non Oboe 6,826x4,000, 14x1,000, 23,657x500 pound HE, 8x4,000, 347x1,000, 15x500, 3,928x250, 10x100, 4,340x4 pound incendiary
Oboe 1,106x4,000, 5,033x500 pound HE, 6x1,000, 10,319x250 pound incendiary