Call:
lm(formula = y ~ x)

Residuals:
     Min       1Q   Median       3Q      Max 
-0.02333 -0.02003 -0.01258  0.00517  0.41195 

Coefficients:
                      Estimate Std. Error t value             Pr(>|t|)    
(Intercept)           0.023326   0.002118  11.013 < 0.0000000000000002 ***
xLow income          -0.008813   0.004768  -1.848              0.06495 .  
xLower middle income -0.010435   0.003834  -2.722              0.00665 ** 
xNA                  -0.019857   0.007305  -2.718              0.00672 ** 
xUpper middle income -0.003266   0.003541  -0.922              0.35659    
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1

Residual standard error: 0.03699 on 707 degrees of freedom
Multiple R-squared:  0.01941,	Adjusted R-squared:  0.01386 
F-statistic: 3.499 on 4 and 707 DF,  p-value: 0.007693