想求问一下3个问题：如何使坐标轴长度不超过刻度上限？实线和虚线中间断了是怎么回事？如何合并两个图例？
ggplot(data=test1,aes(x=year,y=val,col=sex,shape=predict,linetype=predict))+
  theme_classic(base_family = "")+
  theme(text=element_text(size=10,face = "bold", family="serif"))+
  geom_point()+
  geom_line()+
  scale_shape_manual(values = c(16,1))+
  scale_linetype_manual(values = c('solid', 'dotted')) +
  labs(title='Global Age−standardized DALYs Rate of Cirrhosis due to NASH')+
  theme(plot.title = element_text(hjust = 0.5)) +
  scale_x_continuous(name="Year", breaks=seq(1990,2050,10),limits=c(1990, 2050)) +
  scale_y_continuous(name="Age−standardized DALYs Rate
  Per 100k Population", breaks=seq(30,60,10),limits=c(30, 60))+
  theme(legend.title=element_blank())+
  theme(legend.text = element_text(size = 8, face = "plain"))+
  theme(legend.position = 'top')