Call:
lm(formula = y ~ x)

Residuals:
     Min       1Q   Median       3Q      Max 
-0.02136 -0.01239 -0.00576  0.00455  0.34844 

Coefficients:
                      Estimate Std. Error t value             Pr(>|t|)    
(Intercept)           0.021366   0.001565  13.649 < 0.0000000000000002 ***
xLow income          -0.016139   0.003524  -4.580         0.0000054894 ***
xLower middle income -0.015593   0.002833  -5.503         0.0000000521 ***
xNA                  -0.013867   0.005398  -2.569             0.010413 *  
xUpper middle income -0.008970   0.002617  -3.428             0.000643 ***
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1

Residual standard error: 0.02734 on 707 degrees of freedom
Multiple R-squared:  0.0588,	Adjusted R-squared:  0.05347 
F-statistic: 11.04 on 4 and 707 DF,  p-value: 0.00000001084