two_colors=c('darkorange2','firebrick')

ggplot(data, aes(Aster_experience, R_experience)) +
  geom_point(aes(size=coverage, color=product)) +
  geom_text(aes(label=product), size=5, nudge_x=0.0, nudge_y=-0.15) +
  geom_hline(yintercept=0) + geom_vline(xintercept=0) +
  labs(x="Aster Experience", y="R Experience", title="R Packages for Teradata Aster") +
  scale_x_continuous(limits=c(-1,1), breaks=c(-.8,.8), labels=c('less','more')) +
  scale_y_continuous(limits=c(-1,1), breaks=c(-.8,.8), labels=c('less','more')) +
  scale_size(range=c(15,20)) +
  scale_color_manual(values=two_colors, guide="none") +
  theme(axis.text.y = element_text(angle = 90, hjust = 1),
        axis.ticks = element_blank(),
        axis.text=element_text(size=12),
        axis.title=element_text(size=14,face="bold"),
        plot.title=element_text(size=18, vjust=1))