X=[598.00  349.00  461.00 57482.00 20729.00   44.00
       586.00  455.00  475.00 58796.00 21364.00   89.00
       707.00  520.00  491.00 60266.00 21832.00   97.00
       737.00  558.00  529.00 61465.00 22328.00   98.00
       825.00  715.00  556.00 62828.00 23018.00  150.00
       837.00  798.00  575.00 64653.00 23711.00  139.00
       1028.00 1235.00  598.00 65994.00 26600.00  256.00
       1114.00 1681.00  509.00 67207.00 26173.00  338.00
       1079.00 1870.00  444.00 66207.00 25880.00  380.00
       757.00 1156.00  434.00 65859.00 25590.00  138.00
       677.00  964.00  461.00 67295.00 25110.00   66.00
       779.00 1046.00  514.00 69172.00 26640.00   85.00
       943.00 1250.00  584.00 70499.00 27736.00  129.00
      1152.00 1581.00  632.00 72538.00 28670.00  175.00
      1322.00 1911.00  687.00 74542.00 29805.00  212.00
      1249.00 1647.00  697.00 76368.00 30814.00  156.00
      1187.00 1565.00  680.00 78534.00 31915.00  127.00
      1372.00 2101.00  688.00 80671.00 33225.00  207.00
      1638.00 2747.00  767.00 82992.00 34432.00  312.00
      1780.00 3156.00  790.00 85229.00 35620.00  355.00
      1833.00 3365.00  789.00 87177.00 35854.00  354.00
      1978.00 3684.00  855.00 89211.00 36652.00  374.00
      1993.00 3696.00  891.00 90859.00 37369.00  393.00
      2121.00 4254.00  932.00 92421.00 38168.00  462.00
      2052.00 4309.00  955.00 93717.00 38834.00  443.00
      2189.00 4925.00  971.00 94974.00 39377.00  454.00
        2475.00 5590.00 1058.00 96259.00 39856.00  550.00
        2702.00 6065.00 1150.00 97542.00 40581.00  564.00
        2791.00 6592.00 1194.00 98705.00 41896.00  568.00
       2927.00 6862.00 1273.00 100072.0 43280.00  496.00];
y=[184.00 216.00 248.00 254.00 268.00 286.00 357.00 444.00 506.00 ... 
   271.00 230.00 266.00 323.00 393.00 466.00 352.00 303.00 447.00 ...
   564.00 638.00 658.00 691.00 655.00 692.00 657.00 723.00 922.00 ...
   890.00 826.00 810.0]';
beta0=[0.50 -0.03 -0.60 0.01 -0.02 0.35];
betafit = nlinfit(X,y,'model',beta0)