如何减少matplotlib中分组条形图子图之间的间距?

import matplotlib
import matplotlib.pyplot as plt
import numpy as np

a_means, a_CI = (70, 60), (2.7, 1.9)
b_means, b_CI = (85, 83), (2.6, 1.2)
c_means, c_CI = (66, 64), (3.5, 1.8)

ind = np.arange(2)
width = 0.35

fig, ax = plt.subplots(figsize=(10, 4), facecolor='w', edgecolor='k')
rects1 = ax.bar(ind - 2*width/4, a_means, width/4, yerr=a_CI, label='a')
rects2 = ax.bar(ind - width/4, b_means, width/4, yerr=b_CI, label='b')
rects3 = ax.bar(ind, c_means, width/4, yerr=c_CI, label='c')

ax.set_xticks(ind)
ax.set_ylim([50, 100])
ax.legend(loc='upper center', bbox_to_anchor=(0.5, -0.1),
          fancybox=True, shadow=True, ncol=3)

plt.show()

这就是我得到的: old

这就是我想要的: new

有什么办法可以做到这一点吗?提前谢谢!