R version 2.9.0 (2009-04-17)
Copyright (C) 2009 The R Foundation for Statistical Computing
ISBN 3-900051-07-0

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> x <- c(556,555,554,552,572,571,556,546,547,547,548,550,555,549,555,550,566,573,543,535,542,541,535,536,548,546,548,548,561,563,527,527,541,534,522,527,539,533,532,519,538,542,503,502,522,511,492,500,509,511,505,493,518,518,474,471,483,461,439,446,461,449,441,424,447,448,404,403,411,386,359,370,385,369,368,352,378,383,334,323,330,303,275,284,301,281,284,272,297,300,240,236,247,218,192,201,223,197,195,175,197,204,142,142,151,127,100,114,139,112,123,108,132,140,76,71,81,57,38,46)
> par4 = '12'
> par3 = 'Deze reeks geeft het aantal bezoekers per maand weer van 01/'00-12/'09'
Error: unexpected numeric constant in "par3 = 'Deze reeks geeft het aantal bezoekers per maand weer van 01/'00"
Execution halted