Hello stata users, I am having troubles with rownumb() in my code. Below is the code and data.

Code:

Code:
 version 10.1
drop _all
set memory 512m
set more off
set matsize 800

local outdir "E:\Today\"

cd "E:\Today\"


******************* load macro data into matrix ************************

*import delimited E:\Today\data.txt, clear 

insheet using data.txt, clear

mkmat year
mkmat p
mkmat cpi
mkmat yrret

local myrs = rowsof(yrret)
local rowyrs ""

forvalues i=1/`myrs' {
   local addyr = year[`i',1]
   local rowyrs "`rowyrs' `addyr'"
   }
matrix rownames p = `rowyrs'
matrix rownames cpi = `rowyrs'
matrix rownames yrret = `rowyrs'
global yroffset = year[`myrs',1]-`myrs'
matrix yrs = (1955,1960,1962,1963,1964,1967,1968,1969,1970,1971,1977,1983,1986,1989,1992,1995,1998,2001,2004,2007)
global nyrs = colsof(yrs) 

qui gen f = 0
qui gen w = 0
qui gen lret = . 
qui gen yri = rownumb(yrret,string(year)) 
forvalues i=1/136 {
  quietly replace lret = yrret[yri-`i',1] if yri > `i'  
  qui replace f = f + lret if yri > `i'
  qui replace w = w + 1 if yri > `i'
  } 
qui gen retall = f/w 
drop yri
drop f
drop w
drop lret
Error message using rownumb():

Code:
. qui gen yri = rownumb(yrret,string(year)) 
type mismatch
r(109);
Data:

Code:
* Example generated by -dataex-. To    install:    ssc    install    dataex
clear
input int year float(p cpi yrret)
1871 4.6916666 12.400645 .3783405
1872  5.029167  12.92396 .3891352
1873  4.801667 12.678156 .3787354
1874      4.57 11.940774 .3827223
1875    4.4475  11.26684 .3947424
1876 4.0608335  10.50566 .3865376
1877  3.135833  10.11715 .3099522
1878  3.383333 8.6423855 .3914814
1879    4.1225 8.5234585 .4836652
1880  5.209167  9.538342 .5461291
1881  6.254167  9.776216 .6397329
1882       5.9 10.307447 .5724017
1883  5.634167  9.562134 .5892165
1884 4.7408333  8.816821 .5377033
1885  4.596667  8.087381 .5683751
1886  5.364167  7.754368 .6917607
1887  5.534167  8.039808 .6883456
1888  5.204167 8.1825285 .6360096
1889  5.323333  7.738511 .6879015
1890  5.269166  7.794014  .676053
1891  5.028333  7.770226 .6471283
1892      5.55  7.270711 .7633366
1893     4.775  7.445147 .6413574
1894  4.386667  6.660196 .6586393
1895     4.525  6.802913 .6651562
1896  4.233333  6.461975 .6551145
1897 4.4508333   6.49369 .6854089
1898    5.0525  6.747412 .7488056
1899  6.288333   7.28657 .8630032
1900    6.1475   7.80987  .787145
1901    7.8425  7.690938 1.019707
1902  8.416667  8.182522 1.028615
1903  7.211667  8.285602 .8703854
1904  7.049167  8.277667 .8515885
1905  8.985833  8.356963 1.075251
1906  9.621667  8.571018 1.122582
1907      7.84  9.070535 .8643371
1908  7.775833  8.737544 .8899336
1909    9.7125  9.435274 1.029382
1910  9.351666  9.768285 .9573499
1911     9.235  9.007118   1.0253
1912     9.535  9.601766 .9930465
1913    8.5075  9.883333 .8607926
1914     7.945 10.016667  .793178
1915     8.305 10.108333 .8215994
1916  9.466667 10.883333 .8698316
1917     8.495    12.825 .6623782
1918  7.539167 15.041667 .5012189
1919    8.7825 17.333332 .5066827
1920    7.9775  20.04167 .3980457
end
Suggestions will be very much appreciated.