fitting gamma probability density function

 Hello,

I have data Y [1x40]:

Y = [ -0.0063 -0.0025 -0.0012 0 0 -0.0005 -0.0005 -0.0005 -0.0005 -0.0003 -0.0003 0 0 0.0023 0.0229 0.0416 0.0378 0.0262 0.0135 0.0080 0.0036 0.0021 0.0021 0.0023 0.0029 0.0031 0.0031 0.0029 0.0029 0.0029 0.0016 0.0016 0.0020 0.0020 0.0020 0.0020 0.0020 0.0025 0.0025 0.0020 ]

and data X [1x40]

X = [ 0 1.7140 3.4280 5.1420 6.8560 8.5700 10.2840 11.9980 13.7120 15.4260 17.1400 18.8540 20.5680 22.2820 23.9960 25.7100 27.4240 29.1380 30.8520 32.5660 34.2800 35.9940 37.7080 39.4220 41.1360 42.8500 44.5640 46.2780 47.9920 49.7060 51.4200 53.1340 54.8480 56.5620 58.2760 59.9900 61.7040 63.4180 65.1320 66.8460 ]

I want to approximate it by gamma probability density function and get the shape and scale parameters. How can I do this?

I have tried to use nlinfit, but I get bad approximation.

Do I need to shift the curve to the left that the start of the curve's peak is at zero?

Thanks for a reply.

Donatas