Call:
lm(formula = y ~ x)

Residuals:
     Min       1Q   Median       3Q      Max 
-0.16857 -0.04133 -0.01601  0.01618  0.42510 

Coefficients:
                     Estimate Std. Error t value             Pr(>|t|)    
(Intercept)           0.16940    0.01106  15.321 < 0.0000000000000002 ***
xLow income          -0.15772    0.01983  -7.953    0.000000000000487 ***
xLower middle income -0.12803    0.01719  -7.449    0.000000000007952 ***
xNA                  -0.01601    0.07973  -0.201                0.841    
xUpper middle income -0.09351    0.01692  -5.527    0.000000148772560 ***
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1

Residual standard error: 0.07896 on 144 degrees of freedom
Multiple R-squared:  0.3839,	Adjusted R-squared:  0.3668 
F-statistic: 22.43 on 4 and 144 DF,  p-value: 0.00000000000002056